BUREAD OF ANIMAL INDUSTRY. 503 



teriura of swine plague, not obtained pure from the pig, was thus isolated 

 by passing tlirough mice. 



In another case, Ko. 100, in which the mucous membrane of the 

 cfecum was a single mass of necrosed tissue and most of the other 

 lesions found in swine plague were present, cover-glass preparations 

 of the spleen, blood, and a few lymphatic glands were negative. One 

 liquid culture of the blood and two of the spleen remained sterile. A 

 platinum wire, di))ped into the blood and spleen substance, was drawn 

 through layers of gelatine on plates, I^Tot a single colony appeared, 

 Tbe animal penned with the former, No. 101, also died of swine plague, 

 as shown on post mortem examination, but complicated with a localized 

 peritonitis in the region, of the liver. The liquid cultures from the 

 peritoneal eli'usion and blood grew more vigorously than swine plague 

 bacteria, and on gelatine the colonies remained very smalL In several 

 later attempts at plate cultures, they entirely failed to grow. The 

 microbe resembled that of swine j)lague. In both pigs (Xos. 100 and 

 101) the common bile-duct was completely occluded and greatly dis- 

 tended by about ten ascarides, extending from the duodenum into the 

 smaller bile-ducts. This may account for the peritonitis found in l^o. 

 101. The fact that it is difficult to demonstrate the presence of the bac- 

 terium of swine plague in chronic cases which have lasted more than 

 three weeks, and in wliich the ulcerations in the large intestine are 

 already far advanced (Plate I) cannot be emphasized too much. In 

 those cases in which the disease leads to a sudden fatal termination, the 

 bacterium, as a rule, is found abundantly in the spleen. Ignorance of 

 these facts has no doubt led to previous erroneous deductions in investi- 

 gations on the etiology of this disease. Clironic swine-plague must 

 henceforth be looked upon as an after stage, independent of the disease 

 itself, and caused by intestinal lesions, the indirect result of the growth of 

 the bacterium in the blood vessels of the mucous and submucous tissue. 

 The bacterium has already disapj^eared from the stage and makes way 

 frequently for other either harmless or septic microbes, which gain en- 

 trance through the ulcerated membrane and are found in tbe blood and 

 serous exudates. An epidemic of swine jdague, which broke out among 

 a herd of pigs destined for experimental purposes, illustrates the gen- 

 eral statement above very well. This epidemic which, most fortunately, 

 appeared after the experiments recorded in the preceding pages had 

 been completed, and cast no doubt on the results obtained, was very 

 severe and showed the great mortality in herds in which the disease 

 has gained a foothold. The disease was, without doubt, introduced 

 with the herd, and the lesions found on 2:>ost mortem all pointed to chronic 

 cases of three or four weeks standing. Of twenty-five animals exi)osed 

 to the disease only two remained well. All the diseased animals died in 

 periods varying from two to four weeks after exposure. Each case was 

 carefully examined and cover-glass preparations made from the spleen 

 of every anminal. Out of fifteen animals only two had a few bacteria 

 in the spleen. Of but three of these liquid cultures were made, for 

 want of time. These three remained sterile. This is very significant 

 when we compare with these latter results those obtained from acute 

 cases. It goes far to pro re that the majority of the animals affected 

 with swine plague die from the sequeloe of the disease, and but few from 

 the direct effect of the microbes multiplying in the blood vessels of the 

 internal organs. 



It is hardly necessary to recall once more the important fact that in 

 all these cases no bacillus resembling that found in Pasteur's vaccine, 

 and proved to be the cause of rouget on the continent of Europe, ever 



